Which category? Adobe is not even close to being the leader in the CMS category. WP, Wix, Squarespace, Joomla!, Shopify… how does Adobe fit here?
[0] https://w3techs.com/technologies/details/cm-adobeexperiencem...
Wix, Squarespace, and Shopify are Tier 3 CMSs at best.
Drupal, (managed) WordPress, Joomla, Cake, Webflow etc. are Tier2.
AEM, Sitecore, BloomReach, Contentful, Contentstack, etc. are Tier 1
The CMS ecosystem is further segmented into products that are headless, decoupled, hybrid, and monolithic. To complicate things, there is a new type of product called DXP (Digital Experience Platform), which mixes in marketing systems into the stack.